/* Copyright  (c) 2002 Graz University of Technology. All rights reserved.
 *
 * Redistribution and use in  source and binary forms, with or without 
 * modification, are permitted  provided that the following conditions are met:
 *
 * 1. Redistributions of  source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in  binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *  
 * 3. The end-user documentation included with the redistribution, if any, must
 *    include the following acknowledgment:
 * 
 *    "This product includes software developed by IAIK of Graz University of
 *     Technology."
 * 
 *    Alternately, this acknowledgment may appear in the software itself, if 
 *    and wherever such third-party acknowledgments normally appear.
 *  
 * 4. The names "Graz University of Technology" and "IAIK of Graz University of
 *    Technology" must not be used to endorse or promote products derived from 
 *    this software without prior written permission.
 *  
 * 5. Products derived from this software may not be called 
 *    "IAIK PKCS Wrapper", nor may "IAIK" appear in their name, without prior 
 *    written permission of Graz University of Technology.
 *  
 *  THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE LICENSOR BE
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 *  OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 *  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY  OF SUCH DAMAGE.
 */

package iaik.pkcs.pkcs11;

import iaik.pkcs.pkcs11.wrapper.CK_SLOT_INFO;
import iaik.pkcs.pkcs11.wrapper.Constants;
import iaik.pkcs.pkcs11.wrapper.Functions;



/**
 * Objects of this class represet slots that can accpet tokens. The application
 * can get a token object, if there is one present, by calling getToken.
 * This may look like this:
 * <pre><code>
 *   Token token = slot.getToken();
 *
 *   // to ensure that there is a token present in the slot
 *   if (token != null) {
 *     // ... work with the token
 *   }
 * </code></pre>
 *
 * @see iaik.pkcs.pkcs11.SlotInfo
 * @see iaik.pkcs.pkcs11.Token
 * @author <a href="mailto:Karl.Scheibelhofer@iaik.at"> Karl Scheibelhofer </a>
 * @version 1.0
 * @invariants (module_ <> null)
 */
public class Slot {

  /**
   * The module that created this slot object.
   */
  protected Module module_;

  /**
   * The indentifier of the slot.
   */
  protected long slotID_;

  /**
   * The constructor that takes a reference to the module and the slot ID.
   *
   * @param module The reference to the module of this slot.
   * @param slotID The identifier of the slot.
   * @preconditions (pkcs11Module <> null)
   * @postconditions
   */
  protected Slot(Module module, long slotID) {
    if (module == null) {
      throw new NullPointerException("Argument \"module\" must not be null.");
    }
    module_ = module;
    slotID_ = slotID;
  }

  /**
   * Compares the slot ID and the module_ of this object with the slot ID and
   * module_ of the other object. Returns only true, if both are equal.
   *
   * @param otherObject The other Slot object.
   * @return True, if other is an instance of Slot and the slot ID and module_
   *         of both objects are equal. False, otherwise.
   * @preconditions
   * @postconditions
   */
  public boolean equals(Object otherObject) {
    boolean equal = false;

    if (otherObject instanceof Slot) {
      Slot other = (Slot) otherObject;
      equal = (this == other)
              || ((this.slotID_ == other.slotID_)
                  && this.module_.equals(other.module_));
    }

    return equal ;
  }

  /**
   * Get the module that created this Slot object.
   *
   * @return The module of this slot.
   * @preconditions
   * @postconditions
   */
  public Module getModule() {
    return module_ ;
  }

  /**
   * Get the ID of this slot. This is the ID returned by the PKCS#11
   * module.
   *
   * @return The ID of this slot.
   * @preconditions
   * @postconditions
   */
  public long getSlotID() {
    return slotID_ ;
  }

  /**
   * Get information about this slot object.
   *
   * @return An object that contains informatin about this slot.
   * @exception TokenException If reading the information fails.
   * @preconditions
   * @postconditions (result <> null)
   */
  public SlotInfo getSlotInfo()
      throws TokenException
  {
    CK_SLOT_INFO ckSlotInfo = module_.getPKCS11Module().C_GetSlotInfo(slotID_);

    return new SlotInfo(ckSlotInfo) ;
  }

  /**
   * Get an object for handling the token that is currently present in this
   * slot, or null, if there is no token present.
   *
   * @return The object for accessing the token. Or null, if none is present
   *         in this slot.
   * @exception TokenException If determining if a token is present fails.
   * @preconditions
   * @postconditions
   */
  public Token getToken()
      throws TokenException
  {
    Token token = null;

    if (getSlotInfo().isTokenPresent()) {
      token = new Token(this);
    }

    return token ;
  }

  /**
   * The overriding of this method should ensure that the objects of this class
   * work correctly in a hashtable.
   *
   * @return The hash code of this object. Gained from the slot ID.
   * @preconditions
   * @postconditions
   */
  public int hashCode() {
    return (int) slotID_ ;
  }

  /**
   * Returns the string representation of this object.
   *
   * @return the string representation of this object
   */
  public String toString() {
    StringBuffer buffer = new StringBuffer();

    buffer.append("Slot ID: ");
    buffer.append("0x");
    buffer.append(Functions.toHexString(slotID_));
    buffer.append(Constants.NEWLINE);

    buffer.append("Module: ");
    buffer.append(module_.toString());

    return buffer.toString() ;
  }

}
